Wafer surface observation apparatus

ABSTRACT

A dicing apparatus for moving a wafer quickly to a desired observation position before the wafer surface is observed. The apparatus comprises imaging means for imaging the surface of a wafer, display means for displaying the image picked up by the imaging means, input means for inputting position information by designating an arbitrary position displayed by the display means, by using the display position on the display means, conversion means for converting the inputted position information into positional information on the position of the wafer surface, and moving means for moving the display position on the basis of the converted positional information. The apparatus displays the image in the displayed position moved.

TECHNICAL FIELD

The present invention relates to a wafer observation positiondesignating apparatus and a wafer display position designating methodand particularly relates to a wafer observation position designatingapparatus and a wafer display position designating method whereby asurface of a wafer is picked up image by a microcamera and the like, theimage of the wafer surface is displayed, and a pattern on the wafersurface is observed.

BACKGROUND ART

Conventionally wafer surface observation apparatuses are known whereby awork placed on a mounting table is enlarged and picked up image by amicrocamera and the like to set a processing standard and observeprocessing results. A display range on a wafer which is enlarged anddisplayed by the conventional wafer surface observation apparatus islimited to just a part of an area on the wafer. Thus, when anobservation position is changed, the operator operates an axis drivebutton or a joystick so that each axis is driven and the position of thecamera relative to the wafer is moved. Thus, the imaging range of thecamera is moved to a desired position.

However, in the wafer surface observation apparatus which moves anobservation position on a surface of a wafer by using the conventionalaxis drive button or joystick as input means, since the input means ismeans for inputting a rate vector, there is a problem that it isdifficult to position the observation position swiftly on a fine patternformed on the wafer surface.

The present invention is devised in view of such circumstances and hasas its object the provision of a wafer observation designating apparatusand a wafer display position designating method whereby a microcameracan be swiftly moved to a desired observation position with ease.

DISCLOSURE OF THE INVENTION

In order to attain the above object, a wafer observation positiondesignating apparatus according to the present invention is a waferobservation position designating apparatus for observing a pattern on asurface of a wafer, comprising image pickup means for picking up imageof the surface of the wafer, display means for displaying an imagepicked up by the image pickup means, input means for inputting positioninformation by designating an arbitrary position displayed by thedisplay means, by using a position on the display, conversion means forconverting the inputted position information into position informationabout the wafer surface, and moving means for moving a display positionaccording to the converted position information about the wafer surface,wherein the display means displays the image of the display positionafter the movement.

According to the wafer observation position designating apparatus of thepresent invention, when a surface of a wafer is observed, quick movementis able to be made to a desired display position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a dicing device according to thepresent invention;

FIG. 2 is a plan view showing the dicing device according to the presentinvention;

FIG. 3 is a block diagram showing an information processing section ofthe dicing device;

FIG. 4 is a flowchart showing steps for alignment model registration ofa standard wafer W;

FIG. 5 is a diagram showing the contents of initial display provided ondisplay means;

FIG. 6 is a diagram showing contents displayed in a direct touch mode;and

FIG. 7 is a flowchart showing a method of designating a display positionon a touch screen.

BEST MODE FOR CARRYING OUT THE INVENTION

The following will describe a preferred embodiment of a waferobservation position designating apparatus and a wafer display positiondesignating method of the present invention in accordance with theaccompanying drawings.

FIG. 1 is a perspective view showing a dicing device according to thewafer observation position designating apparatus and the wafer displayposition designating method of the present invention. FIG. 2 is a planview showing the dicing device.

The dicing device is constituted of a cutting section 10 for observing asurface of a wafer (work) W and cutting the wafer W in crossingdirections to finally have a lattice pattern, a cleaning section 20 forcleaning the cut wafer W, a cassette 30 for storing processed andunprocessed wafers W, an elevator 40 for drawing the unprocessed wafer Wfrom a desired position of the cassette 30, prealigning the wafer W on astage, and storing the processed wafer W, which has been set on thestage, on a desired position of the cassette 30, and a carrying device50 for carrying the wafer in the above steps.

As shown in FIG. 2, as carrying positions for the wafer W carried by thecarrying device 50, four positions P1, P2, P3, and P4 are available. Thepositions P1 to P4 are arranged on the four corners of a square.Additionally, the position P1 is a position where the wafer W ispreloaded, the position P2 is a position where the wafer W isloaded/unloaded on a cutting table for carrying the wafer W to thecutting section 10, the position P3 is a position where the wafer W isloaded/unloaded on a spinner table of the cleaning section 20, and theposition P4 is a position where the unprocessed wafer W is loaded andthe processed (cleaned) wafer W is unloaded.

The cutting section 10 is constituted of two spindles 16A and 16B havingblades 14A and 14B, respectively, imaging means 18 and 19 which performfine alignment by imaging a pattern on the wafer W with a camera andrecognizing the image of the pattern, and display means 12 whichdisplays a picked up image and various kinds of information andcomprising input means 11 represented by a touch screen. The spindles16A and 16B of the cutting section 10 and the imaging means 18 and 19can move along arrow A-B (Y axis direction) of FIG. 2. Further, sincethe cutting table having the wafer W thereon can move along arrow C-D (Xaxis direction) and can rotate (in θ direction), the surface of thewafer W is imaged and is subjected to image processing, and finealignment can be carried out for cutting.

The wafer W having been subjected to the fine alignment is cut by theblades 14A and 14B rotated by the spindles 16A and 16B according to themovement of the cutting table. Then, the cutting is sequentially carriedout so as to cut the wafer W in a lattice pattern.

The cleaning section 20 is provided for cleaning the cut wafer W. First,the spinner table having the wafer W thereon is moved down and the waferW is cleaned with a spinner and clean water. After cleaning, the wafer Wis dried with air and then the spinner table is moved up.

Moreover, the carrying device 50 is constituted of a slide arm which ismovably attached to a rail guided in the Y axis direction, a swivel armwhich is attached so as to freely pivot on the end of the slide arm, anda plurality of chucks which are attached to the ends of the swivel arm.The slide arm is moved forward/backward by a motor along the rail andthe end of the slide arm is moved between the position P2 and theposition P3. The swivel arm is caused to pivot on the end of the swivelarm by the motor and the end of the swivel arm is moved to the positionsP1, P2, P3, and P4 according to the position of the slide arm. Thechucks are each attached to the end of the swivel arm so as to freelyrotate and has four claws for sandwiching the wafer W. The claws move inthe diameter direction and vertical direction.

FIG. 3 shows a block diagram showing an information processing sectionof the dicing device.

As shown in FIG. 3, the information processing section of the dicingdevice comprises input means 11 allowing the operator to input commandsfor starting, stopping, and moving an observation position, displaymeans 12 for enabling the dicing device to display a processing mode, aprocessing state, and an image of a wafer surface to the operator, andimaging means 18 and 19.

Further, the information processing section of the dicing devicecomprises drive means including X-drive means 100 for moving the cuttingtable having the wafer W thereon in the X axis direction, Y-drive means102 for moving the spindles 16A and 16B of the cutting section 10 andthe imaging means 18 and 19 in the Y axis direction, Z-drive means 104for moving the spindles 16A and 16B and the imaging means 18 and 19 ofthe cutting section 10 in the Z axis direction, and θ-drive means 106for rotating the cutting table having the wafer W thereon in the θdirection, and the information processing section comprises controlmoans 110 for outputting a driving command to each of the drive meansand monitoring a driving position, a driving velocity, and errorinformation when necessary, and information processing means 112 whichtransmits and receives information to and from the input means 11, thedisplay means 12, the imaging means 18 and 19, and the control means 110and controls the overall dicing device.

Moreover, the information processing means 112 has the function ofconversion means which receives on-screen position information about adesired position inputted by the operator in an image of a wafer surfacehaving been displayed by the display means 12, and converts the inputtedposition information to position information about the wafer surface,the function of moving means which moves a display position according tothe converted position information about the wafer surface, and thefunction of moving means which moves the display position to thereference position of a wafer pattern. Besides, the informationprocessing means 112 has the function of shape detecting means whichdetects reference information about a street pattern formed on a wafersurface, and comprises storage means such as a hard disk or anonvolatile memory for storing the reference information.

Additionally, the information processing means 112 has the function ofposition calculating means which receives on-screen position informationabout a desired position inputted by the operator in an image of a wafersurface having been displayed by the display means 12 and calculates theposition or the reference position of a street pattern closest to theinputted position information on the display, and the function ofconversion means which converts information about the calculatedposition of the street pattern on the display into position informationabout the wafer surface according to the reference information about thestreet pattern, reference information being stored in the storage means.

FIG. 4 is a flowchart showing the alignment model registration of astandard wafer W. The registration is made by the dicing device.

When it is necessary to register an alignment model of the wafer W inthe cutting process performed by the dicing device on the wafer W, asshown in FIG. 4, the processing program of the information processingmeans 112 invokes step S100 “Register alignment model” (hereinafterabbreviated as S100) of a processing routine for the alignment modelregistration. Thereafter, the routine proceeds to the subsequent stepS102 “Workload.”

In S102, the two or more unprocessed wafers W having been stored in thecassette 30 are drawn in sequence by the elevator 40 and the wafers Ware set on the position P4 of FIG. 2. Then, the wafers W are placed on awork table (not shown) (on the position P2) via a preloading stage onthe position P1 by the carrying device 50 and the wafers W are suckedand held thereon.

A pattern on the surface of the wafer W, which has been carried to thework table and is sucked and held thereon, is imaged by the imagingmeans 18 or 19 having been automatically moved to the center of the worktable, and the pattern is displayed on the display means 12 and issubjected to image recognition by the image processing means 112. Theroutine proceeds to the subsequent step S104 “Manual θ alignment.”

In S104, the θ axis is aligned so that the street of the work is inparallel with the X axis. At this point, the rotation input of the θaxis is instructed according to the steps below.

The center of the imaging means 18 or 19 is aligned with a street edgeand the like in the vicinity of the center of the work on CH1 side(first channel indicating an axis in parallel with the X axis) andregistration is made in the internal memory of the informationprocessing means 112 (the central position is determined). According tothe present invention, in the method of designating a display position(method of “aligning”) by aligning the center of the imaging means 18 or19 with the street edge and the like in the vicinity of the center ofthe work, the operator only has to touch a position on the display means12 with a finger to designate the position as described bellow.

FIG. 5 shows the contents of initial display on the display means 12.FIG. 6 shows contents displayed in a direct touch mode.

As shown in FIG. 5, the display means 12 comprises a start button 120for input to start the operation of the dicing device, a stop button 122for input to stop the operation, a focus adjusting button 124 foradjusting the focuses of the imaging means 18 and 19, an illuminationadjusting button 126 for adjusting the luminance of illumination duringimaging, an XY key 128 for inputting a moving vector when an imagingposition is moved, and a direct touch moving button 130 for providing aninstruction for switching to a mode in which a desired position(position on the display) on the displayed wafer W is designated withthe touch of a finger.

FIG. 6 shows display for change when the direct touch moving button ispressed in the state of FIG. 5. As shown in FIG. 6, the display means 12additionally displays a cancel button 132 for inputting an instructionto cancel the direct tough moving mode and a wafer map display 134 forindicating the overall shape of the wafer W. Instead of the wafer mapdisplay 134, an enlarged image obtained by imaging may be displayed.

FIG. 7 is a flowchart showing the method of designating a displayposition on the touch screen.

When the dicing device is set in the direct touch mode, the processingprogram of the dicing device invokes a processing routine shown in FIG.7. The program is branched to step S200 “Touch screen to startprocessing.”

When the operator touches a desired position for movement with a finger,the processing program proceeds to the subsequent step S202 “Acquiretouch coordinates (pixel size) (X coordinates/Y coordinates).” In S202,inputted position information (position information about pixels on thescreen or coordinate values and so on based on the resolving power ofthe touch screen) on the touch screen (input means 11) is sent to theinformation processing means 112 via communication means of the inputmeans 11, so that the information processing means 112 acquires thetouch coordinates.

In the subsequent step S204 “Convert touch coordinates into dicercoordinates (pulse coordinates),” the information processing means 112of the dicing device converts the received position information intodisplayed position information about the surface of the wafer W (theinformation includes a unit of an actual length or a driving unit pulsenumber and the like used for the driving of the drive means). In thiscase, the position information on the display is automatically convertedaccording to the size of the wafer (a size and shape of 5 inches, 8inches, etc.) and thus the operator can input a desired position usingthe same operating method regardless of the size of the wafer.

In the subsequent step S206 “Calculate current pulse coordinates ofdicer and a relative amount (travel distance) of converted pulsecoordinates,” the information processing means 112 converts theconverted position information about the surface of the wafer W into,for example, a travel distance relative to the current image position onthe X axis and the Y axis (length information or driving pulse number oneach of the axes).

In the subsequent step S208 “Output calculated travel distance of X-axismotor and travel distance of Y-axis motor to each axis driver,” theinformation processing means 112 outputs the information about thecalculated travel distance to the control means 110.

In the subsequent step S210 “Start and stop axis movement,” the controlmeans 110 sets accelerating conditions, decelerating conditions, anddriving velocity conditions based on the received information about thetravel distance and drives each axis in a synchronous manner.

The control means 110 monitors the driving condition of each axis everymoment and controls the driving velocity of each axis. When movement ismade to the position designated by the information processing means 112,the control means 110 replies to the information processing means 112that the movement is completed.

The on-screen position information inputted by the operator is generallydifferent from information about an accurate street position (positionof a predetermined pattern) because the position is inputted with afinger. In most cases, when a position on the surface of the wafer W isdesignated in the use of the dicing device, a street position isdesignated. In the present invention, even when an imprecise position isdesignated, a display position is moved to a reference position such asa street position obtained near the imprecise position by imageprocessing.

The on-screen position information inputted by the operator is convertedon the position closest to a street pattern detected by the patterndetecting function of the information processing means 112 or theposition closest to one or more reference positions of a pattern formedon the wafer surface, the reference positions being stored in thestorage means. An instruction to move to the position is outputted tothe control means 110. Then, the display position is moved to a positionhaving the closest street to the position inputted by the operator.

After movement is made to the designated position, the program of theinformation processing means proceeds to step S212 “Reflect X coordinateposition and Y coordinate position on screen after movement, Redisplaycross on image screen and center of camera, Redisplay wafer map displayscreen and camera icon.” When the driving of the drive means iscompleted, the display means 12 displays the wafer surface of thedesignated display position. When the wafer map display 134 isredisplayed, a camera icon indicating an imaging position is alsoredisplayed. Further, when an enlarged image having been picked up isdisplayed, a + mark is displayed at the imaging center of the imagingmeans. When a picked up image has a wide imaging range and a highresolving power, only image data having been picked up may be used tomove the display position, instead of driving the drive means to movethe display position.

When movement to the designated position and redisplay are completed,the processing program proceeds to step S214 “Complete processing” andreturns to the initial processing routine.

In this way, when the center of the imaging means 18 or 19 is moved to astreet edge and so on in the vicinity of the center of the work or“alignment” is performed using direct touch for moving a displayposition, the X axis automatically moves to the left (or right) end ofthe work. Then, by direct touch, alignment is made with the edge of thesame street as the position designated at the center, and the left(right) position is determined. Thus, the rotation angle of the θ axisis calculated based on the coordinates of the center position and theleft (right) position and the θ axis is rotated and moved according tothe angle.

After the left (right) position is determined, the X axis automaticallymoves to the vicinity of a work edge on the opposite side. In a similarmanner, the center of the imaging means 18 or 19 is aligned with thestreet edge by direct touch. After the right (left) position isdetermined, the rotation angle of the θ axis is automaticallycalculated, the θ axis is rotated and moved, and the X axisautomatically moves to a position on the opposite side of the work. Thisprocessing is repeated until the X axis and the street are in parallelwith each other. The θ coordinates at this point are recorded in theinternal memory at the completion of scanning.

Thereafter, the θ axis automatically rotates by 90° and the programwaits for input of manual θ alignment on CH2 side (second channelindicating an axis perpendicular to the X axis). Similarly the streetand the X axis are aligned by direct touch and the operation of S104 iscompleted.

In the subsequent step S106 “Register crossing position of CH1 street,”after θ alignment, switching is automatically made to a modelregistration mode and the imaging means is moved to the vicinity of thecenter of the work. The imaging means 18 or 19 is aligned with anintersection point (crossing position) of the CH streets by direct touchand registration is made.

In the subsequent step S108 “Register CH1 first (high magnification)model,” after the crossing position is registered, switching is made toa model pattern input mode and a model frame is displayed on the screen.The position of the model frame is aligned with a proper position bydirect touch and registration is made.

In the subsequent step S110 “Register CH2 second (low magnification)model,” the imaging magnification of the imaging means 18 or 19 isautomatically switched to a low magnification and the model isregistered by direct touch as in the case of a high magnification model.After registration, the θ axis automatically rotates by 90° and theimaging means 18 or 19 moves to the vicinity of the center of the work.

In the subsequent step S112 “Register crossing position of CH2 street,”the imaging magnification of the imaging means 18 or 19 is automaticallyswitched to a high magnification and the intersection point of thestreet is registered as a crossing position by direct touch as in thecase of CH1.

In the subsequent step S114 “Register CH2 first (high magnification)model,” the screen is automatically switched to the model registrationmode as in the case of CH1, and a CH2 high magnification model isregistered by direct touch. The steps are similar to those of CH1.

After “Register CH2 first (high magnification) model” in step S114, theprogram proceeds to step S116 “Complete model registration” and theregistration of the alignment model is completed.

When the alignment model of the wafer W is registered in the abovemanner, the following alignment is performed before cutting.

The street pattern of the wafer W, which is sucked and held on the worktable, is imaged by the imaging means 18 and 19 and is displayed on thedisplay means 12. Then, the pattern is subjected to image recognition bythe information processing means 112. Pattern matching is performedbased on the image information and a reference pattern having beenregistered in the storage means, a street is detected, and alignment forcutting is adjusted. Then, the wafer W having been subjected toalignment adjustment is moved in the Y axis direction, which isindicated by arrow A-B shown in FIG. 2, and is moved in the X axisdirection, which is indicated by arrow C-D of the work table, so thattwo streets are cut at the same time. When the first two streets arecut, the spindles 16A and 16B of the cutting section 10 are moved by apitch of the streets in the Y axis direction. Then, the work table ismoved in the X axis direction again, so that the subsequent two streetsare cut. The cutting operation is repeated to cut predetermined streetsin one direction (X direction).

After the predetermined streets are cut, a cutting groove having beencut is imaged by the imaging means 18 or 19 and kerf check isautomatically performed on the cutting groove. In the kerf check,cutting results are inspected which include a degree of chipping (chip)on the wall of the cutting groove and a displacement of the cuttinggroove from the street. In the event of a large chip or a largedisplacement of the cutting groove from the street, an operator call ismade to notify the operator of a malfunction. Moreover, when the cuttinggroove is slightly displaced from the original cutting groove, thecutting position is automatically corrected. When a small chip isobserved, correction such as a change in the cutting condition isperformed and a predetermined number of times of cutting is continuedthereafter. Also in the case of manual kerf check, kerf check can beswiftly conducted by using direct touch as means for moving a displayposition to a desired observation position.

When all the streets are cut in one direction (X direction), the worktable rotates by 90° and streets intersecting the cut streets are cut insequence. Thus, the wafer W is cut finally in a lattice pattern.

After the cutting, the wafer W is returned to the position P2 by thework table and then is carried to the spinner table of the cleaningsection 2 on the position P3 by the carrying device 50. After cleaningwith clean water, the wafer W is dried with air. The cleaned and driedwafer W is carried to the position P4 by the carrying device 50 and thenis stored in the cassette 30 by the elevator 40.

In the above-described embodiment, the touch screen is used as means forinputting position information by designating an arbitrary positiondisplayed by the display means, by using a position on the display. Thepresent invention is not particularly limited and thus a pointing devicesuch as a mouse, a track ball, and a tablet may be used as input means.

Industrial Applicability

As described above, according to the wafer observation positiondesignating apparatus and the wafer display position designating methodof the present invention, when a wafer surface is observed, quickmovement is made to a desired display position.

1. A dicing apparatus, characterized in that the apparatus comprises:image pickup means for picking up image of the surface of the wafer,display means for displaying an image picked up by the imaging means,input means using a pointing device for inputting position informationby designating an arbitrary position displayed by the display means, byusing a position on a display, shape detecting means for detectingreference information of a straight street pattern shape which is formedon the wafer surface according to the image picked up by the imagingmeans, storage means for storing the reference information of thestraight street pattern shape detected by the shape detecting means andone or a plurality of reference position(s) of the straight streetpattern shape formed on the wafer surface, conversion means forconverting the inputted position information into a position closestfrom the inputted position information out of the straight streetpattern shape detected by the shape detecting means, or the positionclosest to the input position information out of the one or a pluralityof reference position(s) of the straight street pattern shape formed onthe wafer surface, according to the reference information, and movingmeans for moving a display position into the converted position inresponse to the inputted position information, wherein after thestraight street pattern shape closest to the position designated by theinput means is matched to the center position of an image picked up bythe imaging means, manual alignment is performed with manual operationto adjust the straight street pattern shape formed on the wafer surfaceand the movement direction during processing to be parallel, by movingthe wafer to a position where the wafer edge is picked up by the imagingmeans in an axial moving direction at processing; and at the movedposition, the edge position of the straight street pattern shape closestto the position designated by the input means which has been matched tothe center position of the image is determined, and the wafer isrotationally moved according to the rotation angle calculated by thecenter position and the edge position.
 2. The dicing apparatus accordingto claim 1, characterized in that when the inputted position informationindicates a position not having the wafer, the conversion means convertsthe inputted position information into wafer position informationclosest to the inputted position.
 3. A dicing apparatus, comprising: animage pickup device for picking up image of the surface of the wafer, adisplay device for displaying an image picked up by the imaging device,an input device using a pointing device for inputting positioninformation by designating an arbitrary position displayed by thedisplay device, by using a position on a display, a shape detectingdevice for detecting reference information of a straight street patternshape which is formed on the wafer surface according to the image pickedup by the image device, a storage device for storing the referenceinformation of the straight street pattern shape detected by the shapedetecting device and one or a plurality of reference position(s) of thestraight street pattern shape formed on the wafer surface, a conversiondevice for converting the input position information into a positionclosest from the input position information out of the straight streetpattern shape detected by the shape detecting means, or the positionclosest to the input position information out of the one or a pluralityof reference position(s) of the straight street pattern shape formed onthe wafer surface, according to the reference information, and a movingdevice for moving a display position into the converted position inresponse to the input position information, wherein after the straightstreet pattern shape closest to the position designated by the inputdevice is matched to the center position of an image picked up by theimage device, manual alignment is performed with manual operation toadjust the straight street pattern shape formed on the wafer surface andthe movement direction during processing to be parallel, by moving thewafer to a position where the wafer edge is picked up by the imagedevice in an axial moving direction at processing; and at the movedposition, the edge position of the straight street pattern shape closestto the position designated by the input device which has been matched tothe center position of the image is determined, and the wafer isrotationally moved according to the rotation angle calculated by thecenter position and the edge position.
 4. The dicing apparatus accordingto claim 3, wherein when the input position information indicates aposition not having the wafer, the conversion device converts the inputposition information into wafer position information closest to theinput position.